Load controllers are often used to control electrical current provided to large electrical or electromechanical loads. An example of such a load is a 3-phase motor, which may be controlled by one or more load controllers. Often times, the load controllers are implemented as high-voltage devices that receive their control signals from a microcontroller, which is operating in a lower voltage environment and is separated from the load controllers by an electrical isolation barrier. Thus, a microcontroller is capable of controlling a large electrical or electromechanical load, such as a 3-phase motor, even though the microcontroller operates in a much different voltage environment. In many instances, the microcontroller is able to control the 3-phase motor via a switching pattern applied by the load controllers in the high-voltage environment.
In the event of a fault where the primary power domain (e.g., the domain in which the microcontroller is situated) is lost, it is desirable to maintain control over the switching functions of the load controllers so that the motor can be shut down safely. Otherwise, the residue current in the motor windings could damage other electronic devices or present a hazard to persons around the motor.
There are many other types of electrical systems that benefit from electrical isolation. Galvanic isolation is a principle of isolating functional sections of electrical systems to prevent current flow, meaning that no direct electrical conduction path is permitted between different functional sections (e.g., distinct power domains are maintained while allowing control signals to pass between the power domains). As one example, certain types of electronic equipment require that high-voltage components (e.g., 1 kV or greater) interface with low-voltage components (e.g., 10V or lower). Examples of such equipment include medical devices and industrial machines that utilize high-voltage in some parts of the system, but have low-voltage control electronics elsewhere within the system. The interface of the high-voltage and low-voltage sides of the system relies upon the transfer of data via some mechanism other than electrical current.
Other types of electrical systems such as signal and power transmission lines can be subjected to voltage surges by lightning, electrostatic discharge, radio frequency transmissions, switching pulses (spikes), and perturbations in power supply. These types of systems can also benefit from electrical isolation.
Electrical isolation can be achieved with a number of different types of devices. Some examples of isolation products include galvanic isolators, opto-couplers, inductive, and capacitive isolators.